The present invention relates to a tracer control system in which pick feed planes can be made uniform in the case of tracing a hemispherical model.
In the case of tracing a model MDL 1 of a three-dimensional configuration such as shown in FIG. 1, for example, by a system which performs tracer control through calculating a trace velocity and a trace direction based on signals available from a tracer head tracing the model surface, the tracing usually takes place following a route a-b-c-d-e-. That is, the tracer head moves from the position a to the trace return position b in the Y-Z plane, a pick feed is carried out to cause the tracer head to move in the X-axis direction at the trace return position b, thence the tracer head moves to the position c in the X-Z plane, and thence moves from the position c to the trace return position d in the X-Z plane again. In this way, the feed axis is turned through 90.degree. between the pick feed and the tracing operation.
In the case of tracing the model MDL 1 shown in FIG. 1, as described above, the pick feed can be effected in the same plane, only by turning the feed axis through 90.degree.. In the case of tracing a hemispherical model MDL 2 such as shown in FIG. 2, for example, if the abovesaid system is applied, the pick feed cannot be effected in a plane parallel to the X-Y plane as in FIG. 1. The solution of this problem is now being demanded.